Читать книгу Anterior Skull Base Tumors - Группа авторов - Страница 10

The anterior skull base can be divided into three segments: a midline and two symmetrically placed segments located laterally. The midline segment is the roof of the nasal cavity and serves as a watershed between the sinonasal tract and the intracranial space, whereas the lateral segments separate the intracranial compartment from the orbital content. Several peculiar anatomical areas make up the midline segment (posterior frontal plate, cribriform plate, ethmoidal roof, planum sphenoidale, and tuberculum sellae), while the lateral segments are more regular, formed by flat laminae (orbital plates of the frontal bones and lesser wings of the sphenoid). Here we detail each segment of the anterior skull base, emphasizing major landmarks, providing classifications and measurements of key areas, and cautioning the endoscopist about areas to avoid or minimize the occurrence of cerebrospinal fluid leaks, as well as providing recommendations and tips. Several endoscopic and sectional macroscopic anatomical images provide the reader with an informative, illustrative, and broad perspective of anterior skull base anatomy.

© 2020 S. Karger AG, Basel

The anatomy of the human skull has not changed in millennia, but following the introduction of lighting, optics, and endoscopes, innovative changes and approaches to the management of diseases and conditions of the nose, paranasal sinuses, and adjacent anatomical areas of the mid-face and anterior skull base (ASB) have occurred. This minimally invasive surgery approach, contrary to open approaches, requires that surgeons acquire detailed knowledge of local anatomy as viewed from in to outwards, allowing for a safe, targeted, and bloodless approach while pursuing the view seen from an endoscope. This surgical approach involves not only the nasoethmoidal box, but also the adjacent anatomic areas, which are not infrequently the target of so-called extended transnasal endoscopic approaches.

For this reason, the authors considered it important that the reader be updated with a review of the ASB together with photographic documentation that allows for detailed understanding of the anatomic structures encountered in a transnasal endoscopic journey toward the ASB and beyond the nose. In addition, details on the endoscopic view of the ASB via extra-nasal endoscopic approaches, as the transorbital or the supraorbital, are included.

Fig. 1. The midline segment of the ASB is made up of the posterior plate of the frontal sinus (pink area), cribriform plate (CP, red area), crista galli (CG), ethmoidal roof (ER, green area), planum sphenoidale (PS, dark blue area), and tuberculum sellae (TuS, light blue area). The lateral segment of the ASB is formed by the orbital plate of the frontal bone (OPFB) and lesser wing of the sphenoid bone (LWSB), which serves as the roof of both the orbit (yellow area) and optic canal (orange area). The anterior and posterior ethmoidal arteries run below or within the ethmoidal roof (red dashed lines) and enter the anterior cranial fossa through the anterior (AES) and posterior (PES) ethmoidal sulci, branching in the anterior meningeal arteries (red continuous lines). The middle meningeal artery provides the blood supply for the dura of the anterior cranial fossa through some branches of the frontal division (red continuous line on the far left). It also gives rise to the meningo-ophthalmic/meningo-lacrimal artery (red continuous line on the left), which enters the orbit (red dashed line) and provides a recurrent branch for the dura of the lesser sphenoid wing. The black dashed line represents the frontosphenoidal suture. ACP, Anterior clinoid process; OC, optic canal; OS, optic strut.